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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.state.gemini.engine.snapshot;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.base.IntSerializer;
import org.apache.flink.api.common.typeutils.base.LongSerializer;
import org.apache.flink.api.common.typeutils.base.MapSerializer;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.api.java.typeutils.runtime.TupleSerializer;
import org.apache.flink.core.fs.FileStatus;
import org.apache.flink.core.fs.FileSystem;
import org.apache.flink.core.fs.Path;
import org.apache.flink.runtime.state.gemini.engine.dbms.GContext;
import org.apache.flink.runtime.state.gemini.engine.exceptions.GeminiRuntimeException;
import org.apache.flink.runtime.state.gemini.engine.fs.FileIDImpl;
import org.apache.flink.runtime.state.gemini.engine.fs.FileManager;
import org.apache.flink.runtime.state.gemini.engine.memstore.WriteBufferManager;
import org.apache.flink.util.Preconditions;
import org.apache.flink.shaded.guava18.com.google.common.util.concurrent.ThreadFactoryBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
/**
* Implementation of {@link SnapshotManager}.
*/
public class SnapshotManagerImpl implements SnapshotManager {
private static final Logger LOG = LoggerFactory.getLogger(SnapshotManagerImpl.class);
public static final String SNAPSHOT_DIR = "snapshot";
public static final String SNAPSHOT_FILE_PREFIX = "snapshot";
public static final String SNAPSHOT_FILE_SEPERATOR = "-";
private final boolean localSnapshotEnabled;
private final FileManager localFileManager;
private final FileManager dfsFileManager;
private boolean needToBreakLineage;
private final WriteBufferManager writeBufferManager;
private final SortedMap completedSnapshots;
private final SortedMap runningSnapshot;
private final SortedSet runningSnapshotAccessNumber;
private volatile long minRunningSnapshotAccessNumber;
private final ExecutorService snapshotExecutor;
private final GContext gContext;
public SnapshotManagerImpl(
GContext gContext,
WriteBufferManager writeBufferManager,
FileManager localFileManager,
FileManager dfsFileManager) {
this.gContext = gContext;
this.writeBufferManager = writeBufferManager;
this.localFileManager = localFileManager;
this.dfsFileManager = dfsFileManager;
this.completedSnapshots = new ConcurrentSkipListMap<>();
this.runningSnapshot = new ConcurrentSkipListMap<>();
this.runningSnapshotAccessNumber = new TreeSet<>();
this.minRunningSnapshotAccessNumber = Long.MAX_VALUE;
this.localSnapshotEnabled = gContext.getGConfiguration().isLocalSnapshotEnabled();
String prefix = gContext.getGConfiguration().getExcetorPrefixName();
ThreadFactory namedThreadFactory = new ThreadFactoryBuilder().setNameFormat(prefix + "geminiMainSnapshot-%d").build();
this.snapshotExecutor = new ThreadPoolExecutor(1,
1,
0L,
TimeUnit.MILLISECONDS,
new LinkedBlockingQueue(Short.MAX_VALUE),
namedThreadFactory);
LOG.info("SnapshotManager is created.");
}
@Override
public boolean isNeedToBreakLineage() {
return needToBreakLineage;
}
/**
* Note this method should be called before restoreLineage.
*/
@Override
public void setNeedToBreakLineage(boolean needToBreakLineage) {
this.needToBreakLineage = needToBreakLineage;
}
@Override
public void startSnapshot(BackendSnapshotMeta backendSnapshotMeta) {
gContext.checkDBStatus();
long checkpointId = backendSnapshotMeta.getCheckpointId();
Preconditions.checkArgument(!runningSnapshot.containsKey(checkpointId), checkpointId + " is already running.");
gContext.increaseCurVersion();
// increment and record access number to protect files used by this snapshot will not be deleted when DB discards them.
gContext.incAccessNumber();
long accessNumber = gContext.getAccessNumber();
synchronized (runningSnapshotAccessNumber) {
runningSnapshotAccessNumber.add(accessNumber);
minRunningSnapshotAccessNumber = runningSnapshotAccessNumber.first();
}
long startTime = System.currentTimeMillis();
LOG.info("GeminiDB start checkpoint {}, start time {}, access number {}.",
checkpointId,
startTime,
accessNumber);
try {
SnapshotOperation snapshotOperation = localSnapshotEnabled ?
new LocalAndDFSSnapshotOperation(gContext, this, dfsFileManager, localFileManager) :
new DFSSnapshotOperation(gContext, this, dfsFileManager);
PendingSnapshot pendingSnapshot = snapshotOperation.createPendingSnapshot(
backendSnapshotMeta, accessNumber);
runningSnapshot.put(checkpointId, pendingSnapshot);
SnapshotCompletableFuture snapshotCompletableFuture = pendingSnapshot.getResultFuture();
snapshotCompletableFuture.incRunningTask();
writeBufferManager.doSnapshot(snapshotOperation);
snapshotCompletableFuture.decRunningTask();
pendingSnapshot.getSnapshotStat().setSyncStartTime(startTime);
pendingSnapshot.getSnapshotStat().setAsyncStartTime(System.currentTimeMillis());
} catch (Throwable e) {
// fow now we catch everything and rethrow to see if we should do some error handle later.
synchronized (runningSnapshotAccessNumber) {
runningSnapshotAccessNumber.remove(accessNumber);
minRunningSnapshotAccessNumber = runningSnapshotAccessNumber.first();
}
throw e;
}
}
@Override
public void endSnapshot(long checkpointId, Throwable throwable) {
PendingSnapshot pendingSnapshot = runningSnapshot.remove(checkpointId);
if (pendingSnapshot != null) {
pendingSnapshot.getSnapshotStat().setCompleteTime(System.currentTimeMillis());
Set dataFileIDs = new HashSet<>();
if (throwable == null) {
// add data files reference if snapshot successfully.
for (int id : pendingSnapshot.getFileMapping().keySet()) {
dfsFileManager.incSnapshotReference(new FileIDImpl(id));
dataFileIDs.add(id);
}
CompletedSnapshot completedSnapshot = new CompletedSnapshot(checkpointId,
pendingSnapshot.getSnapshotMetaPath().toUri().toString(),
dataFileIDs);
completedSnapshots.put(checkpointId, completedSnapshot);
LOG.info("GeminiDB finished checkpoint {}, SnapshotStat {}",
checkpointId, pendingSnapshot.getSnapshotStat());
} else {
LOG.warn("GeminiDB fail to complete checkpoint {}, exception {}", checkpointId, throwable);
}
pendingSnapshot.releaseResource();
// update the access number
synchronized (runningSnapshotAccessNumber) {
runningSnapshotAccessNumber.remove(pendingSnapshot.getAccessNumber());
minRunningSnapshotAccessNumber = !runningSnapshotAccessNumber.isEmpty() ?
runningSnapshotAccessNumber.first() : Long.MAX_VALUE;
}
} else {
LOG.warn("checkpoint {} is not running, and can't be ended.", checkpointId);
}
}
@Override
public long getMinRunningSnapshotAccessNumber() {
return minRunningSnapshotAccessNumber;
}
/**
* Note this method should be called before endSnapshot for the same checkpoint.
*/
@Override
public PendingSnapshot getPendingSnapshot(long checkpointId) {
PendingSnapshot pendingSnapshot = runningSnapshot.get(checkpointId);
if (pendingSnapshot == null) {
throw new GeminiRuntimeException("there is no pending snapshot " + checkpointId);
}
return pendingSnapshot;
}
@Override
public ExecutorService getSnapshotExecutor() {
return snapshotExecutor;
}
@Override
public void notifySnapshotComplete(long snapshotID) {
// TODO because abort and subsume interface has not been added, we
// discard snapshot here currently, and snapshots whose id are less
// than snapshotID will be discarded.
// TODO the implementation does not consider many cases, such as running snapshots,
// concurrent notify.
Iterator> iterator = completedSnapshots.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry entry = iterator.next();
if (entry.getKey() >= snapshotID) {
break;
}
iterator.remove();
CompletedSnapshot completedSnapshot = entry.getValue();
for (Integer fileId : completedSnapshot.getDataFileIDs()) {
dfsFileManager.decSnapshotReference(new FileIDImpl(fileId));
}
try {
Path metaPath = new Path(completedSnapshot.getMetaFilePath());
FileSystem.get(metaPath.toUri()).delete(metaPath, false);
} catch (Exception e) {
LOG.error("failed to delete snapshot meta file {}, {}", completedSnapshot.getMetaFilePath(), e);
}
LOG.info("discard snapshot {} when snapshot {} is notified completed", entry.getKey(), snapshotID);
}
}
@Override
public void notifySnapshotAbort(long snapshotID) {
// TODO
}
@Override
public void notifySnapshotSubsume(long snapshotID) {
// TODO
}
@Override
public Map restore(
long snapshotId,
Map fileMapping,
String restoredBasePath) {
Map snapshots;
if (!needToBreakLineage) {
snapshots = loadSnapshots(restoredBasePath, Collections.singleton(snapshotId));
RestoredSnapshot restoredSnapshot = new RestoredSnapshot(
snapshotId,
getDFSSnapshotMetaPath(new Path(restoredBasePath), snapshotId).toUri().toString(),
fileMapping);
snapshots.put(snapshotId, restoredSnapshot);
restoreSnapshots(snapshots);
LOG.info("restore snapshot manager successfully with {} snapshots: {}", snapshots.size(), snapshots.keySet());
} else {
snapshots = Collections.emptyMap();
LOG.info("no snapshot is restored because lineage needs to be broken");
}
return snapshots;
}
@Override
public void close() throws IOException {
snapshotExecutor.shutdownNow();
LOG.info("SnapshotManager is closed");
}
private void restoreSnapshots(Map snapshots) {
for (Map.Entry entry : snapshots.entrySet()) {
long checkpointID = entry.getKey();
RestoredSnapshot restoredSnapshot = entry.getValue();
completedSnapshots.put(checkpointID,
new CompletedSnapshot(checkpointID,
restoredSnapshot.getMetaFilePath(),
restoredSnapshot.getFileMapping().keySet()));
}
}
private Map loadSnapshots(
String restoredDBPath,
Set excludeSnapshots) {
Map snapshots = new HashMap<>();
Path metaDirPath = new Path(restoredDBPath, SNAPSHOT_DIR);
FileStatus[] fileStatusArray;
try {
fileStatusArray = FileSystem.get(metaDirPath.toUri()).listStatus(metaDirPath);
} catch (Exception e) {
LOG.error("failed to list dir status for {} when loading snapshots, {}", metaDirPath, e);
return snapshots;
}
if (fileStatusArray == null) {
return snapshots;
}
for (FileStatus fileStatus : fileStatusArray) {
Path path = fileStatus.getPath();
String fileName = path.getName();
long snapshotID;
try {
snapshotID = getSnapshotID(fileName);
} catch (Exception e) {
LOG.error("failed to get snapshot ID caused by {}", e);
continue;
}
if (excludeSnapshots.contains(snapshotID)) {
LOG.info("skip to load snapshot {}", snapshotID);
continue;
}
try (SnapshotMetaFile.Reader reader = SnapshotMetaFile.getReader(path)) {
// TODO checksum
long fileSize = fileStatus.getLen();
// record the offset of file mapping
reader.seek(fileSize - 16);
long fileMappingOffset = reader.readLong();
reader.seek(fileMappingOffset);
boolean hasFileMapping = reader.readBoolean();
Preconditions.checkState(hasFileMapping, "file mapping should always exist.");
int fileMappingSize = reader.readInt();
// just read base path, but do not use it
reader.readUTF();
Map fileIDToPath = new HashMap<>();
for (int i = 0; i < fileMappingSize; ++i) {
String filePath = reader.readUTF();
Integer id = reader.readInt();
fileIDToPath.put(id, filePath);
}
snapshots.put(snapshotID, new RestoredSnapshot(
snapshotID, path.toUri().toString(), fileIDToPath));
LOG.info("successfully load snapshot {} with {} files", snapshotID, fileIDToPath.size());
} catch (Exception e) {
LOG.error("failed to load snapshot {}, {}", snapshotID, e);
}
}
return snapshots;
}
public Path getDFSSnapshotMetaPath(Path basePath, long checkpointId) {
String name = SNAPSHOT_FILE_PREFIX + SNAPSHOT_FILE_SEPERATOR + checkpointId;
return new Path(basePath, new Path(SNAPSHOT_DIR, name));
}
public Path getLocalSnapshotMetaPath(Path basePath, long checkpointId) {
String name = SNAPSHOT_FILE_PREFIX + SNAPSHOT_FILE_SEPERATOR + checkpointId;
return new Path(basePath, name);
}
@SuppressWarnings("unchecked")
public MapSerializer>> getFileMappingSerializer() {
TupleSerializer> tuple2Serializer = new TupleSerializer<>(
(Class>) (Class) Tuple2.class,
new TypeSerializer[]{IntSerializer.INSTANCE, LongSerializer.INSTANCE}
);
MapSerializer> groupMapSerializer = new MapSerializer<>(
IntSerializer.INSTANCE, tuple2Serializer);
return new MapSerializer<>(IntSerializer.INSTANCE, groupMapSerializer);
}
private long getSnapshotID(String snapshotMetaName) {
String[] splits = snapshotMetaName.split(SNAPSHOT_FILE_SEPERATOR);
if (splits.length == 2 && SNAPSHOT_FILE_PREFIX.equals(splits[0])) {
try {
long snapshotID = Long.valueOf(splits[1]);
if (snapshotID > 0) {
return snapshotID;
}
} catch (Exception e) {
// parse snapshot failed
}
}
throw new IllegalArgumentException("invalid snapshot meta file name " + snapshotMetaName);
}
}
